Typical automotive heating, ventilation and air conditioning modules (HVAC modules) include an electric driven centrifugal fan that spins within a scroll housing to pull unconditioned air from outside (or inside) the vehicle and blow it toward and through a series of heat exchangers and air flow control valves before introduction into the passenger cabin. While the projecting electric motor shaft turns the centrifugal flower, it's main body and heat producing coils are encased within a motor holding that is bolted to the back of the scroll housing, and not directly exposed to any cooling air flow. A cooling air flow for the motor is desirable for motor durability. A conventional motor cooling means often seen in production is a simple tube that runs from an air inlet opening at a high air pressure point within the scroll housing, outside of the housing and around to and through the back of the motor cover, so as to feed a constant cooling air stream to the motor. The cooling tube, though effective, represents an extra part and assembly step, with the consequent extra cost. A cooling tube of this basic type may be seen in U.S. Pat. No. 6,034,451, FIG. 2.
In order to eliminate the extra part, at least some portion of the cooling tube has been molded integrally into the motor cover itself. An inherent problem with the molding operation, however, at least with a simple mold that has no movable cores, is that any duct so formed will inevitably be left open on one side, and will need to be closed off by some other operation and part. This is especially true at the “elbow” of the duct, that is, that portion of the duct that turns the corner and moves radially inwardly toward the back of the motor cover. A known method of so “closing off” and completing the otherwise open duct, while still maintaining moldability of the motor cover as a whole, is shown in FIG. 1. There, a molded motor cover A has an integral, trough shaped duct B, to the end of which is molded an extra flap C, attached by an integral hinge D. Flap C can be folded back over the end of integral duct B, closing off the end thereof while leaving a rectangular window E (in flap C) open. When motor cover A is then bolted to the back of the non illustrated fan scroll, window E can be abutted with another duct formed in the scroll housing to complete a cooling air path from inside the scroll housing, through the window E and ultimately to the motor housing. A drawback of this structure, beyond the extra assembly step of folding over the flap C, is that the abutment of the duct to window E is one of hard plastic to hard plastic, with relatively little tolerance for molding or assembly irregularities at the direct interface.